handleRequest: function handleRequest()

in src/aws-client.js [7423:7508]
78 lines of code
19 McCabe index (conditional complexity)

    handleRequest: function handleRequest(httpRequest, httpOptions, callback, errCallback) {
      var self = this;
      var endpoint = httpRequest.endpoint;
      var emitter = new EventEmitter();
      var href = endpoint.protocol + '//' + endpoint.hostname;
      if (endpoint.port !== 80 && endpoint.port !== 443) {
        href += ':' + endpoint.port;
      }
      href += httpRequest.path;
  
      var xhr = new XMLHttpRequest(), headersEmitted = false;
      httpRequest.stream = xhr;
  
      xhr.addEventListener('readystatechange', function() {
        try {
          if (xhr.status === 0) return; // 0 code is invalid
        } catch (e) { return; }
  
        if (this.readyState >= this.HEADERS_RECEIVED && !headersEmitted) {
          emitter.statusCode = xhr.status;
          emitter.headers = self.parseHeaders(xhr.getAllResponseHeaders());
          emitter.emit(
            'headers',
            emitter.statusCode,
            emitter.headers,
            xhr.statusText
          );
          headersEmitted = true;
        }
        if (this.readyState === this.DONE) {
          self.finishRequest(xhr, emitter);
        }
      }, false);
      xhr.upload.addEventListener('progress', function (evt) {
        emitter.emit('sendProgress', evt);
      });
      xhr.addEventListener('progress', function (evt) {
        emitter.emit('receiveProgress', evt);
      }, false);
      xhr.addEventListener('timeout', function () {
        errCallback(AWS.util.error(new Error('Timeout'), {code: 'TimeoutError'}));
      }, false);
      xhr.addEventListener('error', function () {
        errCallback(AWS.util.error(new Error('Network Failure'), {
          code: 'NetworkingError'
        }));
      }, false);
      xhr.addEventListener('abort', function () {
        errCallback(AWS.util.error(new Error('Request aborted'), {
          code: 'RequestAbortedError'
        }));
      }, false);
  
      callback(emitter);
      xhr.open(httpRequest.method, href, httpOptions.xhrAsync !== false);
      AWS.util.each(httpRequest.headers, function (key, value) {
        if (key !== 'Content-Length' && key !== 'User-Agent' && key !== 'Host') {
          xhr.setRequestHeader(key, value);
        }
      });
  
      if (httpOptions.timeout && httpOptions.xhrAsync !== false) {
        xhr.timeout = httpOptions.timeout;
      }
  
      if (httpOptions.xhrWithCredentials) {
        xhr.withCredentials = true;
      }
      try { xhr.responseType = 'arraybuffer'; } catch (e) {}
  
      try {
        if (httpRequest.body) {
          xhr.send(httpRequest.body);
        } else {
          xhr.send();
        }
      } catch (err) {
        if (httpRequest.body && typeof httpRequest.body.buffer === 'object') {
          xhr.send(httpRequest.body.buffer); // send ArrayBuffer directly
        } else {
          throw err;
        }
      }
  
      return emitter;
    },